OTHER OPTICAL DEVICES

Other optical devices based on CPs which have been proposed have included thermooptic switches and modulators [857, 871]. Such devices would typically use a change in refractive index caused by heating a CP to modulate an optical beam. The change in refractive index with such thermal modulation is usually much greater dian for 

Peyghambarian at the University of Arizona, Tucson, AZ, USA, in collaboration with Marder at CalTech, Pasadena, CA, USA, investigated the use of holographic and phase change properties emanating from 3rd-order NLO effects in CPs for the encryption of credit cards for foolproof identification and to prevent fraud [873]. To date, however, the technology has not been commercially implemented. 

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Light-focusing plastic rods and other optical devices with graduated refractive indexes may use DADC and other monomers (29). Preparation and properties of plastic lenses from CR-39 are reviewed in reference 30. 

Cesium is used in military infrared devices and signal lamps as well as in other optical devices. 

In phosphors and in the ruby laser, light was absorbed and emitted by electrons localised on an impurity site, but in other optical devices, delocalised electrons emit the radiation. In the next section, therefore, we shall consider the absorption and emission of radiation in solids with delocalised electrons, particularly in semiconductors. 

The ability to integrate an electro-optic material with other optical devices, e.g. light sources and detectors, and with electronic drive circuits is important. Integrability implies that the electro-optic materials and the processing of these materials are compatible with the other components, and that electrical and optical interconnects can be fabricated. Polymer glasses are widely used in the fabrication of electronic devices and device interconnects. Polymers are also used as photoresists and as dielectric interlayers for electrical interconnects. As a result, a body of knowledge already exists concerning planarization methods of polymers on substrates, the definition of microscopic features, and the fabrication of microstructures in planar polymer structures. 

Aggarwal, I.D. and Lu, G. (Eds.) (1991) Fluoride Glass Fiber Optics, Academic Press, Boston. Contains a series of chapters written by leading experts in the field detailing the structure, processing, and properties of fluoride glasses and their application as optical fibers and use in other optical devices. 

Fabrications of such fibers with isotropic phase hquid crystals are much eas-iej. 27.29 Because of the fluid property and much lower scatteriug loss, liquid ciystal fibers of much longer dimension have been fabricated and shown to exhibit interesting nonlinear optical properties high quality image transmitting fiber arrays - have also been fabricated for passive pulsed laser limiting applications. Other optical devices based on liquid ciystal filled photonic ciystal (holey) fibers have also been reported. ... 

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